Generate systemd task on the fly

I'm writing a script to backup each mysql databases separately on from a mysql server, but instead of handling this inside the script I would like to rely on systemd to generate a backup job to get all the benefits from systemd (I/O, nice, cgroups).

The script, which would be itself triggered by a systemd timer would list all databases and for each of them launch / create a systemd task for for the current day only.

Is there a command that permit to create systemd ad-hoc task ? it could be a binary but as I plan to write a python script I'm interested to know if some python library would allow this.

best